The present disclosure generally relates to spring coils for innerspring assemblies; and more particularly innerspring assemblies for cushioning articles, such as mattresses.
Traditional spring mattresses generally contain an innerspring assembly having a set of springs that provide cushioning support to one or more users. When a user sleeps on the surface of the mattress, he/she applies a weight on the underlying springs, which in turn compress to provide adequate cushioning support. Typically, lighter users apply less weight on the springs, causing these springs to compress less and thereby providing a different feel from what a heavier person would experience. Consequently, lighter users might experience a different level of comfort as compared to heavier users for a given set of springs. This can present a problem when two sleeping partners are of significantly different weights, for example 120 pounds and 220 pounds. In such cases, one mattress is unlikely to be comfortable for both partners.
One reason that a traditional mattress can be more comfortable to certain users is that they are often constructed with springs having linear spring rates. Such springs compress a distance that is linearly proportional to the weight of the user until they reach full compression. Therefore, traditional springs compress less under a lighter person than under a heavy person. Engineers have attempted to work around this problem by making mattresses having springs with non-linear spring rates (e.g., conical springs). Such non-linear springs can compress significantly under a light person and yet not fully compress under a heavy person, occasionally providing similar levels of comfort for both. However, depending on their exact properties, non-linear springs may only compress linearly unless a certain threshold weight is applied. Therefore, some non-linear springs would have to significantly compress prior to a user experiencing a desired level of comfort. In other words, users would need to be a sufficient weight before they can experience a certain level of comfort provided by the springs' non-linear compression. Besides requiring a heavy user, such significant compression of the innerspring assembly can also be unsuitable for the life of the bed.
Accordingly, it would be generally desirable to provide a cushioned article that provides a similar level of cushioning support for a wide range of users; and it would be particularly desirable for a mattress to be comfortable for users with a broad range of weights.